CN116520303A - Ship-borne ground wave radar target detection method based on self-adaptive beam RDT - Google Patents

Ship-borne ground wave radar target detection method based on self-adaptive beam RDT Download PDF

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CN116520303A
CN116520303A CN202310397012.1A CN202310397012A CN116520303A CN 116520303 A CN116520303 A CN 116520303A CN 202310397012 A CN202310397012 A CN 202310397012A CN 116520303 A CN116520303 A CN 116520303A
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target
rdt
frame
heading
platform
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纪永刚
李桃利
王祎鸣
孙伟峰
王心玲
李发瑞
张昊
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China University of Petroleum East China
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/95—Radar or analogous systems specially adapted for specific applications for meteorological use
    • G01S13/956—Radar or analogous systems specially adapted for specific applications for meteorological use mounted on ship or other platform
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Ocean & Marine Engineering (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention discloses a method for adjusting and repairing beam RDT data in detection and tracking integration of a ship-borne ground wave radar, which relates to the field of ship-borne ground wave radar target detection and comprises the following basic steps: constructing and preprocessing a fixed beam RDT first frame; the suspected target classification and the initial beam determination; judging whether the target is in a detection area or not according to the comprehensive attitude information; RDT beam dynamic determination; RDT repair; DP-TBD target integrated detection; multi-beam target result fusion. The invention fully utilizes the multi-beam data of the ship-borne ground wave radar, and adaptively constructs the beam RDT three-dimensional data based on the target azimuth information and the attitude information of the platform. The beam RDT data is dynamically adjusted in the integrated detection process of the target by combining the motion of the target and the change of the heading of the ship-borne platform, so that the signal-to-noise ratio of the target is improved; for the problem of target signal loss caused by heading change, the invention provides the RDT data repair method, which can continuously carry out the integrated detection process of the target, realize long-time stable tracking of the ship-borne ground wave radar on the target and improve the target detection performance of the ship-borne ground wave radar.

Description

Ship-borne ground wave radar target detection method based on self-adaptive beam RDT
Technical Field
The invention relates to the field of ship-borne ground wave radar target detection, in particular to a detection and tracking integrated method for ship-borne ground wave radar beam RDT self-adaptive construction.
Background
The high-frequency ground wave radar (HFSWR) can realize continuous monitoring of a large range and beyond visual range of an offshore target by utilizing the characteristic of reducing propagation attenuation of vertically polarized electromagnetic waves (3-30 MHz) around the sea surface, and provide information such as the position, the navigational speed, the heading and the like of the moving target in real time. Compared with the traditional shore-based ground wave radar, the ship-borne ground wave radar is flexible, further expands the range of ocean monitoring, and has wide application value in the fields of offshore rights maintenance, offshore traffic management and the like. In the ground wave radar target detection method, the detection and tracking integrated method expands the detection to the time dimension, does not judge whether a target is made by echo data of a single frame, improves the target signal to noise ratio by accumulating multi-frame data, finally completes target detection and track tracking at the same time, and further improves the detection performance of weak target signals in the compact ground wave radar.
The construction of Range-Doppler-Time (RDT) three-dimensional data is a key step of the integration of ground wave radar target detection and tracking. At present, when RDT data is constructed, the existing on-board ground wave radar target detection and tracking integrated method generally uses single-channel echo information or multichannel simple average information, and the signal to noise ratio of targets in the information is generally low, so that detection and tracking of weak targets are not facilitated, and beam data obtained by carrying out beam synthesis on multichannel data has higher signal to noise ratio and can be used for better detection and tracking of the targets. However, for the shipborne ground wave radar, under the influence of ocean power environment elements such as wave currents, the heading of the shipborne platform can be changed drastically in a short time, so that the change of radar detection areas is caused, the change of the azimuth of a target in radar coordinates is aggravated, the situation that the target spans multiple beams in a short time and even some targets are moved out of the radar detection areas occurs. At this time, in the RDT constructed according to the conventional method, the target moving out of the radar detection area lacks an effective echo signal within a period of time, so that the detection and tracking integration for the target cannot be continued, and thus the target track is broken or lost.
The invention provides a ship-borne ground wave radar target detection and tracking integrated method, which fully utilizes target azimuth information and ship-borne platform attitude information, and simultaneously develops integrated detection in multi-beam RDT data. The method for repairing the RDT data is provided for solving the problem that a target signal is temporarily lost due to the severe change of the heading of a platform, so that the integrated detection process of the related target is maintained, and continuous and stable tracking of the related target is realized.
Disclosure of Invention
First, the technical problem to be solved
The invention aims to provide a ship-borne ground wave radar target detection and tracking integrated method constructed based on self-adaptive beam RDT, which is used for carrying out integrated detection in multi-beam RDT data. The problems of track breakage and loss caused by low target signal energy and signal loss under the condition of severe change of the heading of the shipborne platform are solved by fully utilizing radar multichannel data, target azimuth information and attitude information of the platform, continuous and stable tracking of the target is realized, and the detection performance of the shipborne ground wave radar target is improved.
(II) technical scheme
The invention comprises the following steps:
(1) Fixed beam RDT construction and first frame preprocessing
Acquiring multichannel time domain data of a ship-borne radar and attitude data of a ship-borne platform, wherein the attitude data comprises a platform navigational speed v p (k) Platform headingAngle rs of radar main shaft p (k) Etc. Where K represents what frame data, k=1, 2,3,..k, K represents the total frame number of data.
The number of beams required to cover the entire detection area is set to N (set by the actual situation), and an N-beam RDT three-dimensional data structure is constructed. The angle of each beam pointing angle is θ (j), j being numbered counterclockwise for each beam, j=1, 2. Preprocessing (CFAR detection) the head frame data of the constructed fixed beam RDT to obtain a suspected target Point trace data set Point, which comprises a target amplitude value f (unit dB), an azimuth angle alpha (relative to a radar main axis), a radial distance r, a Doppler velocity v and a distance cell r g Doppler cell v g And the longitude lon, the latitude lat, the beam flag (default value-1) with the highest target signal-to-noise ratio and the like.
(2) Suspicious object classification and initial beam determination
Performing beam classification processing on the suspected target Point trace data set Point obtained in the step (1), if the absolute value of the difference value between the target azimuth and the beam pointing angle is minimum, indicating that the target is nearest to the beam, taking the ith target as an example, wherein the signal-to-noise ratio of the target is highest in the beam:
where α (i, k) represents the azimuth of the ith target of the kth frame, θ (j) represents the pointing angle of the jth beam, and flag (i, k) =j represents that the ith target of the kth frame has the highest signal-to-noise ratio in the jth beam.
(3) Comprehensive attitude information for judging whether target is in detection area
Starting from the second frame (k=2), before the detection tracking integrated processing is performed, it is necessary to comprehensively consider the target azimuth angle and the platform heading change amount to determine whether each target is in the radar effective detection area, and the formula is as follows:
wherein b (i, k) =0, indicating that the target exceeds the radar effective detection area at the kth frame; b (i, k) =1, indicating that the target kth frame is still in the radar-effective detection region. Wherein,,the variation of the heading of the kth frame platform is represented, omega is the boundary of the radar effective detection area, and is usually set to be 60 degrees according to actual conditions.
If b (i, k) =1, the process proceeds to step (4).
If b (i, k) =0, it is necessary to determine whether the heading of the shipborne platform is periodically changed, and the target can return to the radar effective detection area again only if the platform is in the periodically changed state. Firstly, acquiring attitude data of a front 20-frame platform, and analyzing whether the platform heading has periodic variation by utilizing Fourier transformation; recombination is carried outAnd judging the change of the heading of the platform.
Where d is the magnitude of the change in heading, and is generally set to 5 °.
s=0, which means that the change amount of the heading of the platform is small, and after the target moves out of the detection area, the target is difficult to return to the detection area again through the change of the heading of the platform, and the detection and tracking integrated process of the target is terminated. s=1, which indicates that the heading is in a periodically changing state and the change amount of the heading is large, and the target can return to the detection area again after moving out of the detection area, and the step (5) is entered.
(4) RDT beam dynamic determination
RDT beam dynamic determination is carried out, and target azimuth and heading change are considered simultaneously, taking a k-1 frame target i as an example:
and flag (i, k) =j, namely the beam where the highest signal-to-noise ratio of the target i of the kth frame is the jth beam, and the jth frame uses the RDT data of the jth beam to perform detection and tracking integration of the target i.
(5) RDT repair
And deleting effective echo signals within a period of time when the target moves out of the radar detection area, predicting the position and amplitude of the target of the next frame through the position and amplitude information of the target of the previous burst in order to continuously detect and track the integrated process of the target, and completing RDT repair.
The distance and speed of the kth frame of the object i are r (i, k-1), v (i, k-1), respectively, and the radial distance r (i, k) of the kth frame of the object can be approximately expressed as follows:
referring to fig. 4, β (i, k-1) is the angle between the target motion direction and the echo direction, and φ (i, k-1) is the angle between the echo direction and the ship-borne platform motion direction; t represents the frame interval time, typically 60s. The included angle β (i, k) between the motion direction of the target and the echo direction of the kth frame also changes:
β(i，k)＝β(i，k-1)+Δβ
frame k stage velocity v p (k) The change of the heading isThe kth frame target speed is as follows:
the unit where the k frame target is can be calculated according to the distance and the speed resolutionLattice (r) g ，v g ). After the position of the target is obtained, the amplitude values of 5 cells centered on the cell in which the target position is located need to be estimated.
Taking three cells expanded from a dimension target as an example, taking the highest m of the distance dimension amplitude of the kth-1 frame of the target and the two secondary high n, p, m and p of the amplitude as a (i, k-1), b (i, k-1) and c (i, k-1), and using the three points to perform Gaussian curve fitting (refer to figure 3), wherein the coordinates H (m', H) of the extreme points of the Gaussian curve are the cells (r) of the kth frame of the target g ，v g ) Is also the amplitude highest point. Then, the difference Deltaμ between the distances corresponding to the highest target amplitudes of the kth frame and the kth-1 frame is calculated, the other two points on the curve are shifted by Deltaμ according to Deltaμ, and the amplitude values b (i, k) and c (i, k) corresponding to the shifted points are obtained.
The estimation of the velocity dimension amplitude value is as above.
(6) DP-TBD target integrated detection
Due to the arrangement of X k X is the target coordinate set in the RD spectrum of the kth frame k ＝{[r g ，v g ，α] T }，r g ∈[1，r max ]，r max V is the distance dimension cell number g ∈[1，v max ]，v max Is the number of speed dimension cells. Set the measured value set of the target echo intensity in the RD spectrum of the kth frame as Z k ＝{z k (r g ，v g ) And), wherein zk (r g ，v g ) Is the target echo intensity measurement in the RD spectrum of the kth frame. Target trackIs defined as:
wherein V is T Is the amplitude threshold. Setting I (x) k ) As a function of the k frame value, ψ k (x k ) Is I (x) k-1 ) Take x corresponding to maximum value k-1 。
When k=1For all x 1 ＝{[r g ，v g ，α] T }∈X 1 Has I (x) 1 )＝z 1 (r g ，v g )，Ψ 1 (x 1 )＝[0，0] T The method comprises the steps of carrying out a first treatment on the surface of the For K is more than or equal to 2 and less than or equal to K, the following are:
when (when)When the real target is confirmed, the unique number trace (i) is corresponding, i=1, 2,3 …, and L are the track numbers. And tracing back the track of the real target to obtain a target track coordinate set.
(7) Multi-beam target result fusion
Because the target track is formed by searching among a plurality of beams, the multi-beam track result fusion is required after all target track searches are completed. If the track of the target in the j-th beam RDT is maintained for m frames and the track in the j+1th beam RDT is maintained for n frames, the two tracks need to be fused into a complete track of m+n frames. In the integrated detection process, each target track has a unique track number trace (i), and when the target dynamically adjusts the beam RDT, the track number is kept unchanged, so that the complete track of the target can be obtained only by correlating target tracks with the same track number.
(III) beneficial effects
The invention has the advantages that:
the invention provides a ship-borne ground wave radar target detection tracking integrated method based on self-adaptive beam RDT, which utilizes multi-beam data, target azimuth information and platform attitude information obtained by a radar, firstly builds an RDT three-dimensional data structure based on different beam information, and carries out first frame data preprocessing; then, carrying out integrated detection by using beam RDT data with the highest target signal-to-noise ratio, and adjusting or repairing the beam RDT data in real time; and finally, fusing the multi-beam results to obtain the complete track of the target. Through adjustment and repair of RDT data, the three-dimensional RDT data of the targets are dynamically changed, so that each target can obtain an optimal echo signal, the signal-to-noise ratio of the target is obviously improved, and the integrated detection and tracking treatment of the targets is facilitated.
Drawings
Fig. 1 is a basic flow chart of the present invention.
Fig. 2 is a diagram illustrating RDT beam dynamic adjustment.
FIG. 3 is a schematic diagram of RDT repair.
Fig. 4 is a schematic diagram of on-board ground wave radar target detection.
Detailed Description
For a better understanding of the objects, contents and advantages of the present invention, the following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings:
referring to fig. 1, the specific implementation steps of the present invention are:
(1) Fixed beam RDT construction and first frame preprocessing
Acquiring multichannel time domain data of a ship-borne radar and attitude data of a ship-borne platform, wherein the attitude data of the ship-borne platform comprises a platform navigational speed v p (k) Platform headingAngle rs of radar main shaft p (k) Etc., the radar main axis is clockwise positive relative to the north direction,/-positive>Where K represents what frame data, k=1, 2,3,..k, K represents the total frame number of data.
In order to prevent the coverage width of adjacent beams from being lower than 3dB, a plurality of beams with different directions are generally set, each beam is pointed at a angle of theta (j) (relative to the main axis of the radar), and j is coded clockwise for each beamNumber, j=1, 2,..n. The relation between beam width and beam pointing angle is as follows, M antenna elements and interval d 0 Is a linear array of beam main lobe widths theta Bw The formula of (2) is:
wherein c is the speed of light, f c Is the radar frequency. The number of beams N (set by the actual situation) required to cover the whole detection area is set, and a three-dimensional data structure of N beams RDT is constructed. Preprocessing the first frame data of the constructed N wave beams RDT, namely CFAR detection and target azimuth estimation, to obtain a suspected target Point trace data set Point, wherein the Point trace information comprises a target amplitude value f (unit dB), an azimuth angle alpha (relative to a radar main axis), a radial distance r, a Doppler velocity v and a distance cell r g Doppler cell v g And the longitude lon, the latitude lat, the beam flag bit (with the default value of-1) with the highest target signal-to-noise ratio and the like.
(2) Suspicious object classification and initial beam determination
And (3) performing beam classification processing on the suspected target Point trace data Point obtained in the step (1), and judging which beam is closest to the target by calculating the difference value of the target azimuth and the central pointing angle of each beam. If the absolute value of the difference between the target azimuth and the beam pointing angle is the smallest, it indicates that the target is nearest to the beam, i.e. the target has the highest signal-to-noise ratio in the beam, such as the ith target:
where α (i, k) represents the azimuth of the ith target of the kth frame, θ (j) represents the pointing angle of the jth beam, and flag (i, k) =j represents that the ith target of the kth frame has the highest signal-to-noise ratio in the jth beam.
(3) Comprehensive attitude information for judging whether target is in detection area
Starting from the second frame (k=2), before the detection tracking integrated processing is performed, it is necessary to comprehensively consider the target azimuth angle and the platform heading change amount to determine whether each target is in the radar effective detection area, and the formula is as follows:
wherein b (i, k) =0, indicating that the target exceeds the radar effective detection area at the kth frame; b (i, k) =1, indicating that the target kth frame is still in the radar-effective detection region. Wherein,,the variation of the heading of the kth frame platform is represented, omega is the boundary of the radar effective detection area, and is usually set to be 60 degrees according to actual conditions.
If b (i, k) =1, the process proceeds to step (4).
If b (i, k) =0, it is necessary to determine whether the heading of the shipborne platform is periodically changed, and the target can return to the radar effective detection area again only if the platform is in the periodically changed state.
Judging whether the platform heading is in effective periodic variation, firstly acquiring the platform attitude data of the previous 20 frames, and analyzing whether the platform heading is in periodic variation by utilizing Fourier transformation instead of changing towards one direction; recombination is carried outAnd judging the change of the heading of the platform.
Where d is the magnitude of the change in heading, and is generally set to 5 °.
s=0, which means that the variation of the heading of the platform is small, the requirement of periodical change of the heading is not met, and after the target moves out of the detection area, the target is difficult to return to the detection area again through the change of the heading of the platform, so that the detection and tracking integrated process of the target is terminated. s=1, which indicates that the heading is in a periodically changing state and the change amount of the heading is large, and after the target moves out of the detection area, the target returns to the detection area again due to the periodically changing heading, and the step (5) is entered
(4) RDT beam dynamic determination
And (3) carrying out RDT beam dynamic determination, namely simultaneously considering the target azimuth and the heading change quantity, solving the sum of the target azimuth of the kth-1 frame and the heading change quantity of the kth frame, then carrying out difference between the sum and each beam pointing angle, and when the absolute value of the difference is minimum, indicating that the kth frame of the target is nearest to the beam, and replacing the target of the next frame into the RDT data of the beam to carry out detection and tracking integrated process. Taking the k-1 frame target i as an example:
and flag (i, k) =j, namely the beam where the highest signal-to-noise ratio of the target i of the kth frame is the jth beam, and the jth frame uses the RDT data of the jth beam to perform detection and tracking integration of the target i.
(5) RDT repair
And deleting effective echo signals within a period of time when the target moves out of the radar detection area, predicting the position and amplitude of the target of the next frame through the position and amplitude information of the target of the previous burst in order to continuously detect and track the integrated process of the target, and completing RDT repair.
Knowing the target i k-1 frame distance, speed, respectively, as r (i, k-1), v (i, k-1), wherein:
v(i，k-1)＝v r (i)cos[β(i，k-1)]+v p (k-1)cos[φ(i，k-1)]
v, described in conjunction with FIG. 4 r (i) Is the true speed of object i, the marine object generally moves at a constant speed, i.e. v r (i) Unchanged; v p (k-1) is the speed of movement of the shipboard platform, β (i, k-1) is the angle between the direction of movement of the target and the direction of echo, and φ (i, k-1) is the angle between the direction of echo and the direction of movement of the shipboard platform.
By cosine law, the radial distance r (i, k) of the kth frame target can be approximated as:
where t represents the frame interval time, typically 60s. The included angle β (i, k) between the motion direction of the target and the echo direction of the kth frame also changes:
β(i，k)＝β(i，k-1)+Δβ
the k frame of ship-borne platform attitude information is known, and the speed is v p (k) Change of headingThe kth frame target velocity v (i, k):
the distance and speed resolution can calculate the cell (r g ，v g ). After the position of the target is obtained, the amplitude values of 5 cells centered on the cell in which the target position is located need to be estimated.
Taking three cells expanded by a distance dimension target as an example, taking the highest m of the distance dimension amplitude of the kth frame of the target and the three points n, p, m, n and p of the two amplitude secondary high points as a (i, k-1), b (i, k-1) and c (i, k-1), and using the three points as Gaussian curve fitting (refer to figure 3), wherein the coordinates H (m', H) of the extreme points of the Gaussian curve are the cells (r) of the kth frame of the target g ，v g ) Is also the amplitude highest point. Then, the difference Deltaμ between the distances corresponding to the highest target amplitudes of the kth frame and the kth-1 frame is calculated, the other two points on the curve are shifted by Deltaμ according to Deltaμ, and the amplitude values b (i, k) and c (i, k) corresponding to the shifted points are obtained.
The estimation of the velocity dimension amplitude value is as above.
(6) DP-TBD target integrated detection
Set X k X is the target coordinate set in the RD spectrum of the kth frame k ＝{[r g ，v g ，α] T }，r g ∈[1，r mnax ]，r mmax V is the distance dimension cell number g ∈[1，v mmax ]，v mmax Is the number of speed dimension cells. Set the measured value set of the target echo intensity in the RD spectrum of the kth frame as Z k ＝{z k (r g ，v g ) -wherein z k (r g ，v g ) For a target echo intensity measurement in the RD spectrum of the kth frame, it is expressed as:
wherein A is k For the target echo amplitude value omega k (r g ，v g ) Is the noise amplitude value. Target trackThe definition is as follows:
wherein V is T Is the amplitude threshold. Setting I (x) k ) As a function of the k frame value, ψ k (x k ) Is I (x) k-1 ) Take x corresponding to maximum value k-1 。
k=1 for all x 1 ＝{[r g ，v g ，α] T }∈X 1 Has I (x) 1 )＝z 1 (r g ，v g )，Ψ 1 (x 1 )＝[0，0] T The method comprises the steps of carrying out a first treatment on the surface of the For K is more than or equal to 2 and less than or equal to K, the following are:
when (when)When the real target is confirmed, the unique number trace (i) is corresponding, i=1, 2,3 …, and L are the track numbers. Track backtracking is carried out on a real target:
in the above formula, k=k-1, K-2. Obtaining a target track coordinate set after completing track backtracking
(7) Multi-beam target result fusion
Because the target track is formed by searching among a plurality of beams, the multi-beam track result fusion is required after all target track searches are completed. If the track of the target in the j-th beam RDT is maintained for m frames and the track in the j+1th beam RDT is maintained for n frames, the two tracks need to be fused into a complete track of m+n frames. In the integrated detection process, each target track has a unique track number trace (i), and when the target dynamically adjusts the beam RDT, the track number is kept unchanged, so that the complete track of the target can be obtained only by correlating target tracks with the same track number.
Repeating the steps (3) (4) (5) (6) for each target until the detection and tracking integrated process of all targets is finished. Therefore, detection and tracking integration of the ship-borne ground wave radar based on the self-adaptive beam RDT is completed, and a target track and a detection result are obtained.
The innovation of the invention is embodied in the following aspects:
the invention fully utilizes the multi-beam data of the ship-borne ground wave radar, and adaptively constructs the beam RDT three-dimensional data based on the target azimuth information and the attitude information of the platform. The beam RDT data is dynamically adjusted in the integrated detection process of the target by combining the motion of the target and the change of the heading of the ship-borne platform, so that the signal-to-noise ratio of the target is improved; for the problem of target signal loss caused by heading change, the invention provides the RDT data repair method, which can continuously carry out the integrated detection process of the target, realize long-time stable tracking of the ship-borne ground wave radar on the target and improve the target detection performance of the ship-borne ground wave radar.

Claims (1)

1. A ship-borne ground wave radar target detection method based on an adaptive beam RDT comprises the following steps:
(1) Fixed beam RDT construction and first frame preprocessing
Acquiring multichannel time domain data of a ship-borne radar and attitude data of a ship-borne platform, wherein the attitude data comprises a platform navigational speed v p (k) Platform headingAngle rs of radar main shaft p (k) Etc. Where K represents what frame data, k=1, 2,3,..k, K represents the total frame number of data.
The number of beams required to cover the entire detection area is set to N (set by the actual situation), and an N-beam RDT three-dimensional data structure is constructed. Each beam is directed at an angle θ (j), j being numbered counterclockwise for each beam, j=1, 2. Preprocessing (CFAR detection) the head frame data of the constructed beam RDT to obtain a suspected target Point trace data set Point, wherein the suspected target Point trace data set Point comprises a target amplitude value f (unit dB), an azimuth angle alpha (relative to a radar main axis), a radial distance r, a Doppler velocity v and a distance cell r g Doppler cell v g And the longitude lon, the latitude lat, the beam flag (default value-1) with the highest target signal-to-noise ratio and the like.
(2) Suspicious object classification and initial beam determination
Performing beam classification processing on the suspected target Point trace data set Point obtained in the step (1), if the absolute value of the difference value between the target azimuth and the beam pointing angle is minimum, indicating that the target is nearest to the beam, taking the ith target as an example, wherein the signal-to-noise ratio of the target is highest in the beam:
where α (i, k) represents the azimuth of the ith target of the kth frame, θ (j) represents the pointing angle of the jth beam, and flag (i, k) =j represents that the ith target of the kth frame has the highest signal-to-noise ratio in the jth beam.
(3) Comprehensive attitude information for judging whether target is in detection area
Starting from the second frame (k=2), before the detection tracking integrated processing is performed, it is necessary to comprehensively consider the target azimuth angle and the platform heading change amount to determine whether each target is in the radar effective detection area, and the formula is as follows:
wherein b (i, k) =0, indicating that the target exceeds the radar effective detection area at the kth frame; b (i, k) =1, indicating that the target kth frame is still in the radar-effective detection region. Wherein,,the variation of the heading of the kth frame platform is represented, omega is the boundary of the radar effective detection area, and is usually set to be 60 degrees according to actual conditions.
If b (i, k) =1, the process proceeds to step (4).
If b (i, k) =0, it is necessary to determine whether the heading of the shipborne platform is periodically changed, and the target can return to the radar effective detection area again only if the platform is in the periodically changed state. Firstly, acquiring attitude data of a front 20-frame platform, and analyzing whether the platform heading has periodic variation by utilizing Fourier transformation; recombination is carried outAnd judging the change of the heading of the platform.
Where d is the magnitude of the change in heading, and is generally set to 5 °.
s=0, which means that the change amount of the heading of the platform is small, and after the target moves out of the detection area, the target is difficult to return to the detection area again through the change of the heading of the platform, and the detection and tracking integrated process of the target is terminated. s=1, which indicates that the heading is in a periodically changing state and the change amount of the heading is large, and the target can return to the detection area again after moving out of the detection area, and the step (5) is entered.
(4) RDT beam dynamic determination
RDT beam dynamic determination is carried out, and target azimuth and heading change are considered simultaneously, taking a k-1 frame target i as an example:
and flag (i, k) =j, namely the beam where the highest signal-to-noise ratio of the target i of the kth frame is the jth beam, and the jth frame uses the RDT data of the jth beam to perform detection and tracking integration of the target i.
(5) RDT repair
And deleting effective echo signals within a period of time when the target moves out of the radar detection area, predicting the position and amplitude of the target of the next frame through the position and amplitude information of the target of the previous burst in order to continuously detect and track the integrated process of the target, and completing RDT repair.
The distance and speed of the kth frame of the object i are r (i, k-1), v (i, k-1), respectively, and the radial distance r (i, k) of the kth frame of the object can be approximately expressed as follows:
referring to fig. 4, β (i, k-1) is the angle between the target motion direction and the echo direction, and φ (i, k-1) is the angle between the echo direction and the ship-borne platform motion direction; t represents the frame interval time, typically 60s. The included angle β (i, k) between the motion direction of the target and the echo direction of the kth frame also changes:
β(i，k)＝β(i，k-1)+Δβ
frame k stage velocity v p (k) The change of the heading isThe kth frame target speed is as follows:
the distance and speed resolution can calculate the cell (r g ，v g ). After the position of the target is obtained, the amplitude values of 5 cells centered on the cell in which the target position is located need to be estimated.
Taking three cells expanded from a dimension target as an example, taking the highest m of the distance dimension amplitude of the kth-1 frame of the target and the two secondary high n, p, m and p of the amplitude as a (i, k-1), b (i, k-1) and c (i, k-1), and using the three points to perform Gaussian curve fitting (refer to figure 3), wherein the coordinates H (m', H) of the extreme points of the Gaussian curve are the cells (r) of the kth frame of the target g ，v g ) Is also the amplitude highest point. Then, the difference Deltaμt of the distance corresponding to the highest target amplitude of the kth frame and the kth-1 frame is calculated, the other two points on the curve are moved by Deltaμ according to Deltaμ, and the amplitude values b (i, k) and c (i, k) corresponding to the moved points are obtained.
The estimation of the velocity dimension amplitude value is as above.
(6) DP-TBD target integrated detection
Due to the arrangement of X k X is the target coordinate set in the RD spectrum of the kth frame k ＝{[r g ，v g ，α] T }，r g ∈[1，r max ]，r max V is the distance dimension cell number g ∈[1，v max ]，v max Is the number of speed dimension cells. Set the measured value set of the target echo intensity in the RD spectrum of the kth frame as Z k ＝{z k (r g ，v g ) -wherein z k (r g ，v g ) Is the target echo intensity measurement in the RD spectrum of the kth frame. Target trackIs defined as:
wherein V is T Is the amplitude threshold. Setting I (x) k ) As a function of the k frame value, ψ k (x k ) Is I (x) k-1 ) Take x corresponding to maximum value k-1 。
k=1 for all x 1 ＝{[r g ，v g ，α] T }∈X 1 Has I (x) 1 )＝z 1 (r g ，v g )，Ψ 1 (x 1 )＝[0，0] T The method comprises the steps of carrying out a first treatment on the surface of the For K is more than or equal to 2 and less than or equal to K, the following are:
when (when)When the confirmation of the real target is completed, corresponding to the unique number trace (i), i=1, 2,3. Track backtracking is carried out on a real target to obtain the targetAnd (5) a track coordinate set.
(7) Multi-beam target result fusion
Because the target track is formed by searching among a plurality of beams, the multi-beam track result fusion is required after all target track searches are completed. If the track of the target in the j-th beam RDT is maintained for m frames and the track in the j+1th beam RDT is maintained for n frames, the two tracks need to be fused into a complete track of m+n frames. In the integrated detection process, each target track has a unique track number trace (i), and when the target dynamically adjusts the beam RDT, the track number is kept unchanged, so that the complete track of the target can be obtained only by correlating target tracks with the same track number.
CN202310397012.1A 2023-04-14 2023-04-14 Ship-borne ground wave radar target detection method based on self-adaptive beam RDT Pending CN116520303A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117749257A (en) * 2024-02-20 2024-03-22 成都星联芯通科技有限公司 Engineering realization method and device for searching high-orbit multi-beam by terminal and terminal equipment
CN117749257B (en) * 2024-02-20 2024-05-17 成都星联芯通科技有限公司 Engineering realization method and device for searching high-orbit multi-beam by terminal and terminal equipment

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